1. Field of the Invention
This invention relates to a refrigerator, and more particularly to a refrigerated air supply apparatus for effectively distributing refrigerated air to different parts of the refrigerator.
2. Description of Background Art
As shown in FIGS. 1 and 2, conventional refrigerators have a freezer compartment 10 and a fresh food compartment 20 partitioned by an insulation barrier 5. The compartments 10, 20 are defined by inner cases 12, 22 respectively surrounded by an insulation material 7 which is cased by an outer case 2. A fan unit 4 for supplying refrigerated air to the freezer compartment 10 and fresh food compartment 20 is mounted in an evaporating chamber 11 provided at the rear portion of the freezer compartment 10. An evaporator 8 for generating refrigerated air is also provided in the evaporating chamber 11. The compartments 10, 20 are respectively closed by doors, 19, 29 hinged in front of the refrigerator. The door 29 has door baskets 26 mounted at inner surfaces thereof for storing food therein.
Conventional refrigerated air circulation will be explained in view of FIGS. 1 and 2. In a refrigeration cycle, refrigerated air is generated by the evaporator 8 in which a working fluid or refrigerant flows. As the fan unit 4 operates, a portion of the refrigerated air flows to the freezer compartment 10, and another portion of the refrigerated air impinges on a grill 16 and is guided to a fresh food duct 24 through a passage 15 defined by a shroud 14 and the grill 16. The refrigerated air guided to the fresh food duct 24 is then blown into the fresh food compartment 20 through a plurality of outlets 25 formed in the front surface thereof, as indicated by the arrows in FIG. 2.
Refrigerated air supplied to the fresh food compartment 20, via the above-mentioned supply path, then moves forward and carries out heat exchange with the food stored in the fresh food compartment 20, thereby becoming relatively warm. The warmed air returns to the evaporating chamber 11 through a return duct 30 formed in the insulation barrier 5 with its inlet 31 adjacent to the door 29. The warmed air in the evaporating chamber 11 carries out heat exchange with the evaporator 8, thereby becoming refrigerated air again.
But the above-described conventional refrigerated air circulation system has a number of problems. First, it lacks the effective uniform cooling of the fresh food compartment 20 since the refrigerated air is provided only in one direction, i.e., forward direction, from the outlets 25 of fresh food duct 24. This means that the temperature of a portion adjacent to the outlets 25 is lower than that of a portion adjacent to the door 29. Therefore, any food stored adjacent to the outlets 25 may be over-refrigerated while any food stored adjacent to the door 29 tends to be under-refrigerated.
Second, the temperature at the door-adjacent portion in the fresh food compartment 20 tends to increase as time passes due to the frequent opening of the door 29. As a result, it takes greater energy and longer time to maintain the temperature of the door-adjacent portion than to maintain the temperature of the portion adjacent to the fresh food duct 24 since refrigerated air is only provided by the fresh food duct 24.
Third, it is difficult to keep the food stored in the door baskets 26 to the temperature desired due to an inflow of warm air from the outside when the door 29 is opened.
An improved refrigerated air circulation system was described in U.S. Pat. No. 5,584,191 issued Dec. 17, 1996. According to this air circulation system, refrigerated air is blown into the fresh food compartment by a cool air duct mounted at the comer of the fresh food compartment and by a door duct which receives the refrigerated air through a transmission duct mounted on a side wall. The transmission duct is exposed to the interior of the fresh food compartment and only delivers refrigerated air which has been spouted out in the fresh food compartment through the cool air duct to the door duct. This air circulation system, however, still has some problems although it improves the uniform refrigerating effect by the spouting the refrigerated air from the door duct.
One problem with the circulation system of U.S. Pat. No. 5,584,191 is that the transmission duct occupies a certain space in the fresh food compartment where food is stored so that a substantial storage space in the fresh food compartment cannot be used because of the presence of transmission duct. Another problem is that the amount of refrigerated air spouted by the door duct is not sufficient since the refrigerated air delivered through the transmission duct is provided to the cool air duct. Still another problem is that a large temperature difference between the fresh food compartment and the interior of the transmission duct causes dewing and freezing on the surface of the transmission duct.